Semiconductor device and its manufacturing method

ABSTRACT

To realize miniaturization/high integration and increase in the amount of accumulated charges, and to give a memory structure having a high reliability. A 1 transistor 1 capacitor (1T1C) structure having 1 ferroelectric capacitor structure and 1 selection transistor every memory cell is adopted, and respective capacitor structures are disposed respectively in either one layer of interlayer insulating films of 2 layers having different heights from the surface of a semiconductor substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2006-015336, filed on Jan. 24,2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device having acapacitor structure sandwiching a ferroelectric film between a lowerelectrode and an upper electrode, and to its manufacturing method. Inparticular, it is preferably applied to a semiconductor device having aferroelectric capacitor structure in which the dielectric film is aferroelectric film having ferroelectric characteristics.

2. Description of the Related Art

Recently, development is proceeded with a ferroelectric memory (FeRAM)holding information in a ferroelectric capacitor structure utilizingpolarization inversion of a ferroelectric substance. The ferroelectricmemory is superior to a flash memory and an EEPROM in low powerconsumption, the number of times of rewriting and speed of rewriting,and used for such applications as IC cards and SIMs. Further, since theferroelectric memory is a nonvolatile memory that does not lose heldinformation when a power source is switched off and can be expected torealize high integration, high speed driving, high durability and lowpower consumption, it particularly attracts attention.

[Patent Document 1] Japanese Patent No. 3591497

Recently, miniaturization/high integration of a semiconductor deviceproceeds more and more, and there also raises similar expectations for aFeRAM. Further, increase in an amount of accumulated charges is alsorequested for such semiconductor memory as a FeRAM. Thus, for a FeRAM,in order to satisfy such conflicting request as miniaturization/highintegration, and increase in an amount of accumulated charges,increasing in an occupying area of a ferroelectric capacitor structurewhile reducing memory cell size is required.

In view of this, Patent Document 1 discloses such constitution as pluralferroelectric capacitor structures formed in plural 2-layered structureshaving a common upper or lower electrode in column direction. However,since the technique of Patent Document 1 has a common upper or lowerelectrode as described above, it is restricted to a special constitutionin which 1 selection transistor is disposed for plural ferroelectriccapacitor structures in column direction. In the constitution, carryingout sufficient integration of a memory cell is difficult.

SUMMARY OF THE INVENTION

The present invention was completed with the view of the above problem,and its object is to provide a semiconductor device capable of realizingminiaturization/high integration and increase in an amount ofaccumulated charges and giving a memory structure with a highreliability, and its manufacturing method.

The semiconductor device of the present invention is formed above asemiconductor substrate, wherein 1 memory cell is constituted byincluding 1 capacitor structure sandwiching a dielectric film with alower electrode and an upper electrode, and 1 transistor for selectingthe capacitor structure, and the capacitor structure of respectivememory cells is formed respectively in either 1 layer of at least 2interlayer insulating films having different heights from the surface ofthe semiconductor substrate.

The manufacturing method of the semiconductor device of the presentinvention is a method of manufacturing a semiconductor device providedwith plural memory cells, including the steps of forming transistorsabove a semiconductor substrate, and forming, above the transistor, 1capacitor structure sandwiching a dielectric film with a lower electrodeand an upper electrode so as to correspond to one of the transistors,wherein the capacitor structure of the respective memory cells is formedrespectively in either 1 layer of at least 2 interlayer insulating filmshaving different heights from the surface of the semiconductorsubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are general cross-sectional views showing theconstitution of the stack type FeRAM according to the first embodimentalong with its manufacturing method according to the order of the steps.

FIGS. 2A to 2C are general cross-sectional views, subsequent to theFIGS. 1A to 1C, showing the constitution of the stack type FeRAMaccording to the first embodiment along with its manufacturing methodaccording to the order of the steps.

FIGS. 3A to 3C are general cross-sectional views, subsequent to theFIGS. 2A to 2C, showing the constitution of the stack type FeRAMaccording to the first embodiment along with its manufacturing methodaccording to the order of the steps.

FIGS. 4A to 4C are general cross-sectional views, subsequent to theFIGS. 3A to 3C, showing the constitution of the stack type FeRAMaccording to the first embodiment along with its manufacturing methodaccording to the order of the steps.

FIGS. 5A to 5C are general cross-sectional views, subsequent to theFIGS. 4A to 4C, showing the constitution of the stack type FeRAMaccording to the first embodiment along with its manufacturing methodaccording to the order of the steps.

FIGS. 6A to 6B are general cross-sectional views, subsequent to theFIGS. 5A to 5C, showing the constitution of the stack type FeRAMaccording to the first embodiment along with its manufacturing methodaccording to the order of the steps.

FIGS. 7A to 7B are general cross-sectional views, subsequent to theFIGS. 6A to 6B, showing the constitution of the stack type FeRAMaccording to the first embodiment along with its manufacturing methodaccording to the order of the steps.

FIGS. 8A to 8B are general plan views showing the layout in the vicinityof a ferroelectric capacitor structure of a FeRAM.

FIGS. 9A to 9C are general cross-sectional views showing theconstitution of the stack type FeRAM according to the modified example 1of the first embodiment along with its manufacturing method according tothe order of the steps.

FIGS. 10A to 10B are general cross-sectional views, subsequent to theFIGS. 9A to 9C, showing the constitution of the stack type FeRAMaccording to the modified example 1 of the first embodiment along withits manufacturing method according to the order of the steps.

FIGS. 11A to 11B are general cross-sectional views, subsequent to theFIGS. 10A to 10B, showing the constitution of the stack type FeRAMaccording to the modified example 1 of the first embodiment along withits manufacturing method according to the order of the steps.

FIGS. 12A to 12C are general cross-sectional views showing theconstitution of the stack type FeRAM according to the modified example 2of the first embodiment along with its manufacturing method according tothe order of the steps.

FIGS. 13A to 13C are general cross-sectional views, subsequent to FIGS.12A to 12C, showing the constitution of the stack type FeRAM accordingto the modified example 2 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 14A to 14C are general cross-sectional views, subsequent to FIGS.13A to 13C, showing the constitution of the stack type FeRAM accordingto the modified example 2 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 15A to 15C are general cross-sectional views, subsequent to FIGS.14A to 14C, showing the constitution of the stack type FeRAM accordingto the modified example 2 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 16A to 16C are general cross-sectional views showing theconstitution of the stack type FeRAM according to the modified example 3of the first-embodiment along with its manufacturing method according tothe order of the steps.

FIGS. 17A to 17C are general cross-sectional views, subsequent to FIGS.16A to 16C, showing the constitution of the stack type FeRAM accordingto the modified example 3 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 18A to 18C are general cross-sectional views, subsequent to FIGS.17A to 17C, showing the constitution of the stack type FeRAM accordingto the modified example 3 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 19A to 19C are general cross-sectional views, subsequent to FIGS.18A to 18C, showing the constitution of the stack type FeRAM accordingto the modified example 3 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 20A to 20B are general cross-sectional views, subsequent to FIGS.19A to 19C, showing the constitution of the stack type FeRAM accordingto the modified example 3 of the first embodiment along with itsmanufacturing method according to the order of the steps.

FIGS. 21A to 21C are general cross-sectional views showing theconstitution of the planar type FeRAM according to the second embodimentalong with its manufacturing method according to the order of the steps.

FIGS. 22A to 22C are general cross-sectional views, subsequent to FIGS.21A to 21C, showing the constitution of the planar type FeRAM accordingto the second embodiment along with its manufacturing method accordingto the order of the steps.

FIGS. 23A to 23C are general cross-sectional views, subsequent to FIGS.22A to 22C, showing the constitution of the planar type FeRAM accordingto the second embodiment along with its manufacturing method accordingto the order of the steps.

FIGS. 24A to 24C are general cross-sectional views, subsequent to FIGS.23A to 23C, showing the constitution of the planar type FeRAM accordingto the second embodiment along with its manufacturing method accordingto the order of the steps.

FIGS. 25A to 25C are general cross-sectional views, subsequent to FIGS.24A to 24C, showing the constitution of the planar type FeRAM accordingto the second embodiment along with its manufacturing method accordingto the order of the steps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Basic Gist of thePresent Invention

In the present invention, as a memory cell configuration realizing asignificant increase in an amount of accumulated charges while intendingminiaturization/high integration of a semiconductor memory representedby a FeRAM as far as possible, a 1 transistor 1 capacitor (1T1C)structure having 1 ferroelectric capacitor structure and 1 selectiontransistor every memory cell is adopted, and respective capacitorstructures are disposed respectively in either 1 layer of at least 2interlayer insulating films having different heights from the surface ofa semiconductor substrate.

The 1T1C structure is a structure capable of realizing a further highintegration degree. In the present invention, while intending increasein the integration degree of a memory cell as far as possible on thepremise of a semiconductor memory of this 1T1C structure, by disposingrespective capacitor structures in a hierarchical shape of at least 2layers having different heights from the surface of a semiconductorsubstrate, it becomes possible to increase the occupation area of acapacitor structure in the memory cell.

The present invention can be applied to both of stack type semiconductormemories provided with respective connecting plugs to the downside of alower electrode and the upside of an upper electrode of respectivecapacitor structures, and stack type semiconductor memories providedwith respective connecting plugs to the upside of a lower electrode andthe upside of an upper electrode of respective capacitor structures. Asto the semiconductor memory, application to a FeRAM mainly having aferroelectric dielectric film (ferroelectric film) as a capacitorinsulating film is preferred.

Incidentally, for a FeRAM, influence on the ferroelectric film caused bygeneration of hydrogen becomes problematic. That is, when hydrogenintrudes into a ferroelectric film, it reacts with oxygen of theferroelectric film to form an oxygen defect in the ferroelectric film tolower crystallinity. Further, a similar phenomenon generates due to aprolonged use of a ferroelectric memory, too. As the result, theregenerates such performance degradation of the ferroelectric capacitorstructure as the falloff of an amount of remnant polarization ordielectric constant. Further, by such intrusion of hydrogen, performanceof a transistor and the like, not restricted to the ferroelectriccapacitor structure, may degrade.

Main source origins of hydrogen influencing the ferroelectric film inthis manner include (1) intrusion of moisture from the outside, and (2)generation of hydrogen from a connecting plug.

(1) When moisture intrudes from the outside via an interlayer insulatingfilm having a high affinity with water such as a silicon oxide film, themoisture degrades to hydrogen and oxygen in a high temperature processduring film forming the interlayer insulating film or a metal wiring.This hydrogen intrudes into a ferroelectric film.

(2) When forming a connecting plug, for example, using W as a material,hydrogen is taken in the connecting plug by deposition of W or the likeby a CVD method or the like. The hydrogen intrudes into a ferroelectricfilm.

In addition, for a FeRAM, after patterning a ferroelectric film, it isnecessary to carry out an oxygen annealing treatment in order to recoverdamage given to the ferroelectric film at etching. However, the oxygenannealing treatment may result in abnormal oxidation to a connectingplug.

In the present invention, in respective stack type and planar typeFeRAMs, in order to suppress intrusion of hydrogen into a ferroelectricfilm mainly caused by (1), in respective interlayer insulating films, aprotective insulating film using alumina or the like as a material isformed so as to cover respective capacitor structures.

Further, in a stack type FeRAM, in order to realize suppression ofintrusion of hydrogen mainly cased by (2) into a ferroelectric film, andsuppression of abnormal oxidation of a connecting plug, following (a),(b) constitutions are adopted.

(a) Between a lower electrode and a connecting plug of respectivecapacitor structures, a conductive protective base film, for example,having the same shape as the lower electrode is formed. As theprotective base film, a single layer of TiAlN, a laminated structure ofTiN and TiAlN, or the like is preferred. Incidentally, instead offorming the protective base film, the lower electrode (such as Ir) ofthe ferroelectric capacitor structure may be formed in a thicknesslarger than normal one.

(b) Since, in the present invention, respective ferroelectric capacitorstructures of a FeRAM are disposed in respective interlayer insulatingfilms of at least 2 layers, as a specialized structure for theconstitution, a conductive protective base film is formed into aone-layer structure sandwiched between 2 interlayer insulating filmsadjacently laminated. Respective protective base films constituting thelayer structure are preferably formed between a lower electrode and theconnecting plug for a ferroelectric capacitor of the upper interlayerinsulating film, between an upper electrode and the connecting plug fora ferroelectric capacitor of the lower interlayer insulating film, andbetween the upper and lower connecting plugs (at least one regionthereof), for example, in a shape matching with the upper face of theconnecting plug. As the protective base film, use of a single layer ofTiAlN, a laminated structure of TiN and TiAlN, Ir or the like as amaterial is preferred.

As described above, by forming the protective insulating film or varioustypes of protective base films, it becomes possible to suppress adverseinfluence on the ferroelectric film caused by moisture/hydrogen that isparticularly notably observed for a FeRAM as far as possible, tosuppress abnormal oxidation of a connecting plug, thereby realizing aferroelectric capacitor having a high reliability.

Various Preferred Embodiments the Present Invention is Applied to

Hereinafter, various preferred embodiments in which the presentinvention is applied to a FeRAM of the 1T1C structure will be describedin detail in reference to the drawings. Incidentally, for the sake ofsimplicity of description, constitution of a FeRAM in respectiveembodiments will be described along with its manufacturing method.

First Embodiment

In a first embodiment, the constitution of a stack type FeRAM and itsmanufacturing method are described.

FIGS. 1A to 7B are general cross-sectional views showing theconstitution of the stack type FeRAM according to the first embodimentalong with its manufacturing method according to the order of the steps.

At the beginning, as shown in FIG. 1A, the selection transistor, in theillustrated example, transistor structures 20 a, 20 b, 20 c, 20 d areformed on a silicon semiconductor substrate 10. Here, the transistorstructures 20 a, 20 b, 20 c, 20 d constitute CMOS transistors, wherein20 a, 20 b become NMOS transistors, and 20 c, 20 d become PMOStransistors.

For details, firstly, an element isolating structure 11 is formed on thesurface layer of the silicon semiconductor substrate 10, for example, byan STI (Shallow Trench Isolation) method to determine an element activearea.

Next, a resist mask (not shown) covering the element active area oftransistor structures 20 c, 20 d to become PMOS transistors(hereinafter, referred to as the P active area) and having an aperturecapable of exposing the formation area of transistor structures 20 a, 20b to become NMOS transistors (hereinafter, referred to as the N activearea) is formed.

Then, by using the resist mask, a P type impurity, here boron (B) ision-implanted to the N active area, for example, under such conditionsas a dose amount of 3.0×10¹³/cm² and an acceleration energy of 300 keVto form a P type well 12 a in the N active area. The resist mask isremoved by an ashing treatment or the like.

Next, a resist mask (not shown) covering the N active area and having anaperture capable of exposing the P active area is formed.

Then, using the resist mask, an N type impurity, here phosphorous (P) ision-implanted into the P active area, for example, under such conditionsas a dose amount of 3.0×10³/cm² and an acceleration energy of 600 keV toform an N type well 12 b in the P active area. The resist mask isremoved by an ashing treatment or the like.

Next, thin gate insulating films 13 having a thickness of around 3.0 nmare formed on the P, N active areas respectively by thermal oxidation orthe like, and on the gate insulating film 13 is deposited apolycrystalline silicon film having a thickness of around 180 nm and,for example, a silicon nitride film having a thickness of around 29 nmby a CVD method. Then, by processing the silicon nitride film, thepolycrystalline silicon film and the gate insulating film 13 into anelectrode shape by lithography and subsequent dry etching, gateelectrodes 14 are pattern-formed respectively on the gate insulatingfilms 13 in the P, N active areas. Simultaneously, a cap film 15composed of a silicon nitride film is pattern-formed on respective gateelectrodes 14.

Next, a resist mask (not shown) covering the P active area and having anaperture capable of exposing the N active area is formed.

Then, using the resist mask and the cap film 15 as a mask, an N typeimpurity, here As is ion-implanted into the N active area, for example,under such conditions as a dose amount of 5.0×10¹⁴/cm² and anacceleration energy of 10 keV to form a so-called LDD area 16 a.

Next, for example, a silicon oxide film is deposited by a CVD method onthe whole surface, and the silicon oxide film is subjected to so-calledetch back to form a sidewall insulating film 17 while leaving thesilicon oxide film only on the side faces of the gate electrode 14 andthe cap film 15 in the N active area.

Next, using the resist mask, the cap film 15 and the sidewall insulatingfilm 17 as a mask, an N type impurity, here phosphorous (P) ision-implanted into the N active area under such conditions as giving ahigher impurity concentration than the LDD area 16 a, for example, adose amount of 5.0×10¹⁴/cm² and an acceleration energy of 13 keV to forma source/drain area 18 a to be overlapped to the LDD area 16 a, therebycompleting the transistor structures 20 a, 20 b to become NMOStransistors. The resist mask is removed by an ashing treatment or thelike.

Next, a resist mask (not shown) covering the N active area and having anaperture capable of exposing the P active area is formed.

Then, using the resist mask and the cap film 15 as a mask, a P typeimpurity, here B is ion-implanted into the P active area, for example,under such conditions as a dose amount of 1.0×10¹³/cm² and anacceleration energy of 15 keV to form a so-called LDD area 16 b.

Next, for example, a silicon oxide film is deposited by a CVD method onthe whole surface, and the silicon oxide film is subjected to so-calledetch back to form a sidewall insulating film 17 while leaving thesilicon oxide film only on the side faces of the gate electrode 14 andthe cap film 15 in the P active area.

Next, using the resist mask, the cap film 15 and the sidewall insulatingfilm 17 as a mask, a P type impurity, here B is ion-implanted into the Pactive area under such conditions as giving a higher impurityconcentration than the LDD area 16 b, for example, a dose amount of2.0×10¹³/cm² and an acceleration energy of 5 keV to form a source/drainarea 18 a to be overlapped to the LDD area 16 a, thereby completing thetransistor structures 20 c, 20 d to become PMOS transistors. The resistmask is removed by an ashing treatment or the like.

Subsequently, as shown in FIG. 1B, a protective film 21 and aninsulating film 22 of the transistor structures 20 a, 20 b, 20 c, 20 dare formed.

More specifically, so as to cover the transistor structures 20 a, 20 b,20 c, 20 d, the protective film 21 and the insulating film 22 aredeposited sequentially. Here, as the protective film 21, a silicon oxidefilm is used as a material to be deposited in a thickness of around 20nm by a CVD method. As the insulating film 22, a laminated structureprepared, for example, by sequentially film-forming a plasma SiO film(thickness of around 20 nm), a plasma SiN film (thickness of around 80nm) and a plasma TEOS film (thickness of around 1000 nm) is formed and,after the lamination, it is polished till the thickness becomes around700 nm by chemical mechanical polishing (CMP).

Subsequently, as shown in FIG. 1C, respective plugs 36 to be connectedwith the source/drain areas 18 a, 18 b (as to source/drain area 18 a,either one thereof) of the transistor structures 20 a, 20 b, 20 c, 20 dare formed.

Firstly, respective via holes 34 to the transistor structures 20 a, 20b, 20 c, 20 d are formed.

More specifically, the insulating film 22 and the protective film 21 areprocessed by lithography and subsequent dry etching to form the via hole34 capable of exposing either of the source/drain areas 18 a, and a partof the surface of the source/drain area 18 b respectively.

Next, so as to cover respective wall faces of the via hole 34, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form a base film (glue film) 35. Then, so as toembed the via hole 34 via the glue film 35, a single film or a laminatedfilm of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a W film isformed by a CVD method. After that, the W film and the glue film 35 arepolished by CMP using the insulating film 21 as a stopper to form a plug36 embedding the inside of the via hole 34 with W via the glue film 35.

Subsequently, as shown in FIG. 2A, after forming an anti-oxidizing film37 and a plasma TEOS film 38, respective plugs 42 to be connected withthe other of the source/drain area 18 a of the transistor structures 20a, 20 b are formed.

More specifically, firstly, the anti-oxidizing film 37 of the plug 36 isformed, for example, using SiON as a material in a thickness of around130 nm by a CVD method or the like.

Next, by a plasma CVD method, the plasma TEOS film 38 having a thicknessof around 200 nm is formed.

Next, the plasma TEOS film 38, the anti-oxidizing film 37, theinsulating film 22 and the protective film 21 are processed bylithography and subsequent dry etching to form the via holes 39 capableof exposing a part of the other surface of the source/drain area 18 arespectively.

Next, so as to cover respective wall faces of the via hole 39, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form a base film (glue film) 41. Then, so as toembed the via hole 39 via the glue film 41, a single film or a laminatedfilm of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a W film isformed by a CVD method. After that, the W film and the glue film 41 arepolished by CMP using the plasma TEOS film 38 as a stopper to form aplug 42 embedding the inside of the via hole 39 with W via the glue film41.

Subsequently, as shown in FIG. 2B, a protective base film 43, a lowerelectrode layer 44, a ferroelectric film 45, a lower layer upperelectrode layer 46 and an upper layer upper electrode layer 47 forforming an after-mentioned ferroelectric capacitor structure 30 isformed respectively.

More specifically, firstly, in order to suppress both of abnormaloxidation of the plug 42 caused by an after-mentioned oxygen annealingtreatment of the ferroelectric film 45 and influence of hydrogen takenin the plug 42 upon forming the plug 42 on the ferroelectric film 45,the protective base film 43 being a conductive film is formed in athickness of around 100 nm, for example, by a sputtering method. As amaterial of the protective base film 43, a single layer of TiAlN, alaminated structure of TiN and TiAlN or the like, here a laminatedstructure of TiN and TiAlN is selected.

Next, by a sputtering method, Ir as an example is deposited in athickness of around 100 nm to form the lower electrode layer 44.

Next, by an MOCVD method, the ferroelectric film 45 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 44 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 45 is in an amorphous state in the initial phase of film formation,the ferroelectric film 45 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 45 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 45 in athickness of around 100 nm to form the lower layer upper electrode layer46.

Then, by a sputtering method, for example, Ir is deposited on the lowerlayer upper electrode layer 46 in a thickness of around 100 nm to formthe upper electrode layer 47.

In this connection, as a material of the lower electrode layer 44, theferroelectric film 45, the lower layer upper electrode layer 46 and theupper layer upper electrode layer 47, including the above-describedcase, at least one selected from Ir, IrOx (typically x=2), Pt, SRO, LNO,LSCO, Ru, RuO₂, SrRuO₃ and the like is used respectively.

Subsequently, as shown in FIG. 2C, a hard mask material 48 is formed.

More specifically, on the upper layer upper electrode layer 47, forexample, a TEOS film is deposited in a thickness of around 600 nm by aCVD method or the like to form the hard mask material 48.

Subsequently, as shown in FIG. 3A, the ferroelectric capacitor structure30 of a lower layer is formed.

More specifically, using the hard mask material 48, the upper layerupper electrode layer 47, the lower layer upper electrode layer 46, theferroelectric film 45, the lower electrode layer 44 and the protectivebase film 43 are etched altogether, for example, at 400° C. Then, byremoving the hard mask material 48 by wet etching or the like, theferroelectric capacitor structure 30 is completed in the N active areavia the plug 42 and the protective base film 43, the structure beingconstituted by sandwiching the ferroelectric film 45 with a lowerelectrode 51 composed of the lower electrode layer 44, and an upperelectrode 52 being a laminated structure of the lower layer upperelectrode layer 46 and the upper layer upper electrode layer 47.

Subsequently, as shown in FIG. 3B, a first interlayer insulating film 49covering the ferroelectric capacitor structure 30 is formed.

More specifically, for example, by a high density plasma (HDP) CVDmethod, a silicon oxide film is deposited in a thickness of around 1300nm so as to cover the ferroelectric capacitor structure 30, followed byflattening the surface of the silicon oxide film by CMP to form thefirst interlayer insulating film 49. In the first interlayer insulatingfilm 49, plural (2 in the illustrated example) ferroelectric capacitorstructures 30 are encapsulated. On this occasion, a lower layercapacitor layer 40 is constituted by the ferroelectric capacitorstructure 30 and the first interlayer insulating film 49.

Subsequently, as shown in FIG. 3C, a via hole 53 is formed.

More specifically, by lithography and dry etching, the first interlayerinsulating film 49 is patterned at a site matching with the upside ofthe upper electrode 52 of the ferroelectric capacitor structure 30 toform the via hole 53 capable of exposing a part of the surface of theupper electrode 52.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 30, an oxygen annealing treatment iscarried out. Here, for example, an annealing treatment at a treatmenttemperature of 500° C. in oxygen atmosphere for 60 minutes is carriedout. In the present embodiment, since the protective base film 43 isdisposed between the ferroelectric capacitor structure 30 and the plug42, abnormal oxidation of the plug 42 is prevented even when the oxygenannealing treatment is carried out. Together with that, generation ofhydrogen taken in the plug 42 upon forming the plug 42 is suppressed bythe protective base film 43.

Subsequently, as shown in FIG. 4A, a via hole 54 is formed.

More specifically, by lithography and dry etching, the first interlayerinsulating film 49, the plasma TEOS film 38 and the anti-oxidizing film37 are patterned at a site matching with the upside of the plug 36 toform a via hole 54 capable of exposing at least a part of the surface ofthe plug 36.

Subsequently, as shown in FIG. 4B, respective plugs 57 to be connectedwith the upper electrode 52 of the ferroelectric capacitor structure 30and respective plugs 58 to be connected with the plugs 36 are formed.

More specifically, so as to cover respective wall faces of the via holes53, 54, for example, a TiN film is deposited in a thickness of around 75nm by a sputtering method to form the base films (glue film) 55, 56.Then, so as to embed the via holes 53, 54 via the glue films 55, 56, asingle film or a laminated film of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO orIr, here a W film is formed by a CVD method. After that, the W film andthe glue films 55, 56 are polished by CMP using the first interlayerinsulating film 49 as a stopper to form the plugs 57, 58 embedding theinside of the via holes 53, 54 with W via the glue films 55, 56respectively.

Subsequently, as shown in FIG. 4C, after forming an anti-oxidizing film59 and a plasma TEOS film 61, respective plugs 64 to be connected with apart of the plugs 58 are formed.

More specifically, firstly, an anti-oxidizing film 59 of the plugs 57,58 is formed in a thickness of around 130 nm, for example, using SiON asa material by a CVD method or the like.

Next, by a plasma CVD method, the plasma TEOS film 61 having a thicknessof around 200 nm is formed.

Next, the plasma TEOS film 59 and the anti-oxidizing film 61 areprocessed by lithography and subsequent dry etching to form a via hole62 capable of exposing the surface of a part of the plugs 58respectively.

Next, so as to cover respective wall faces of the via hole 62, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form a base film (glue film) 63. Then, so as toembed the via hole 62 via the glue film 63, a single film or a laminatedfilm of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a W film isformed by a CVD method. After that, the W film and the glue film 63 arepolished by CMP using the plasma TEOS film 61 as a stopper to form theplug 64 embedding the inside of the via hole 62 with W via the glue film63.

Subsequently, as shown in FIG. 5A, after forming a protective base film65, a lower electrode layer 66, a ferroelectric film 67 respectively, alower layer upper electrode layer 68 and an upper layer upper electrodelayer 69 for forming an after-mentioned ferroelectric capacitorstructure 50, a hard mask material 71 is formed.

More specifically, firstly, in order to suppress both of abnormaloxidation of the plug 64 caused by an after-mentioned oxygen annealingtreatment of the ferroelectric film 67 and influence of hydrogen takenin the plug 64 upon forming the plug 64 on the ferroelectric film 67,the protective base film 65 being a conductive film is formed in athickness of around 100 nm, for example, by a sputtering method. As amaterial of the protective base film 65, a single layer of TiAlN, alaminated structure of TiN and TiAlN or the like, here a laminatedstructure of TiN and TiAlN is selected.

Next, by a sputtering method, Ir as an example is deposited in athickness of around 100 nm to form the lower electrode layer 66.

Next, by an MOCVD method, the ferroelectric film 67 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 66 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 67 is in an amorphous state in the initial phase of film formation,the ferroelectric film 67 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 67 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 67 in athickness of around 100 nm to form the lower layer upper electrode layer68.

Then, by a sputtering method, for example, Ir is deposited on the lowerlayer upper electrode layer 68 in a thickness of around 100 nm to formthe upper electrode layer 69.

In this connection, as a material of the lower electrode layer 66, theferroelectric film 67, the lower layer upper electrode layer 68 and theupper layer upper electrode layer 69, including the above-describedcase, at least one selected from Ir, IrOx (typically x=2), Pt, SRO, LNO,LSCO, Ru, RuO₂, SrRuO₃ and the like is used respectively.

Next, on the upper layer upper electrode layer 69, for example, a TEOSfilm is deposited in a thickness of around 600 nm by a CVD method or thelike to form a hard mask material 71.

Subsequently, as shown in FIG. 5B, after forming the ferroelectriccapacitor structure 50 of an upper layer, a second interlayer insulatingfilm 74 covering the ferroelectric capacitor structure 50 is formed.

More specifically, using the hard mask material 71, the upper layerupper electrode layer 69, the lower layer upper electrode layer 68, theferroelectric film 67, the lower electrode layer 66 and the protectivebase film 65 are etched altogether, for example, at 400° C. Then, byremoving the hard mask material 71 by wet etching or the like, theferroelectric capacitor structure 50 is completed in the P active areavia the plug 64 and the protective base film 65, the structure beingconstituted by sandwiching the ferroelectric film 67 with a lowerelectrode 72 composed of the lower electrode layer 66, and an upperelectrode 73 being a laminated structure of the lower layer upperelectrode layer 68 and the upper layer upper electrode layer 69.

Next, for example, by a high density plasma (HDP) CVD method, a siliconoxide film is deposited in a thickness of around 1300 nm so as to coverthe ferroelectric capacitor structure 50, followed by flattening thesurface of the silicon oxide film by CMP to form the second interlayerinsulating film 74. In the second interlayer insulating film 74, plural(2 in the illustrated example) ferroelectric capacitor structures 50 areencapsulated. On this occasion, an upper layer capacitor layer 60 lyingabove the lower layer capacitor layer 40 is constituted by theferroelectric capacitor structure 50 and the second interlayerinsulating film 74.

Subsequently, as shown in FIG. 5C, a via hole 75 is formed.

More specifically, by lithography and dry etching, the second interlayerinsulating film 74 is patterned at a site matching with the upside ofthe upper electrode 73 of the ferroelectric capacitor structure 50 toform the via hole 75 capable of exposing a part of the surface of theupper electrode 73.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 50, an oxygen annealing treatment iscarried out. Here, for example, an annealing treatment at a treatmenttemperature of 500° C. in oxygen atmosphere for 60 minutes is carriedout. In the present embodiment, since the protective base film 65 isdisposed between the ferroelectric capacitor structure 50 and the plug64, abnormal oxidation of the plug 64 is prevented even when the oxygenannealing treatment is carried out. Together with that, generation ofhydrogen taken in the plug 64 upon forming the plug 64 is suppressed bythe protective base film 65.

Subsequently, as shown in FIG. 6A, via holes 76, 77 are formed.

More specifically, by lithography and dry etching, the second interlayerinsulating film 74, the plasma TEOS film 61 and the anti-oxidizing film59 are patterned at a site matching with the upside of the plugs 57, 58to form the via holes 76, 77 capable of exposing at least a part of thesurface of plugs 57, 58 respectively.

Subsequently, as shown in FIG. 6B, respective plugs 82 to be connectedwith the upper electrode 73 of the ferroelectric capacitor structure 50,respective plugs 83 to be connected with the plug 57, and respectiveplugs 84 to be connected with the plug 58 are formed.

More specifically, so as to cover respective wall faces of the via holes75, 76, 77, for example, a TiN film is deposited in a thickness ofaround 75 nm by a sputtering method to form base films (glue film) 78,79, 81. Then, so as to embed the via holes 75, 76, 77 via the glue films78, 79, 81, a single film or a laminated film of W, TiAlN, TiN, Ti, Al,Cu, Ru, SRO or Ir, here a W film is formed by a CVD method. After that,the W film and the glue films 78, 79, 81 are polished by CMP using thesecond interlayer insulating film 74 as a stopper to form the plugs 82,83, 84 embedding the inside of the via holes 75, 76, 77 with W via theglue films 78, 79, 81 respectively.

Subsequently, as shown in FIG. 7A, a barrier metal film 85, a wiringlayer 86 and a barrier metal film 87 are formed sequentially.

More specifically, firstly by a sputtering method, for example, TiN isdeposited in a thickness of around 60 nm to form the barrier metal film85.

Next, by a sputtering method, for example, an Al—Cu alloy is depositedin a thickness of around 360 nm to form the wiring layer 86.

Next, by a sputtering method, for example, a laminated film of TiN andTi is deposited in a thickness of around 70 nm to form the barrier metalfilm 87.

Subsequently, as shown in FIG. 7B, a bit wire 88 to be connected withthe plug 84, and a plate wire 89 to be connected with the plugs 82, 83are formed respectively.

More specifically, the barrier metal film 87, the wiring layer 86 andthe barrier metal film 85 are patterned by lithography and dry etching.By the patterning, respective bit wires 88 to be connected with the plug84, and respective plate wires 89 to be connected with the plugs 82, 83are formed.

After that, through the formation of an interlayer insulating film, anupper layer wiring, a protective insulating film and the like, the stacktype FeRAM according to the present embodiment is completed. In theillustrated example, respective memory cells of the 1T1C structure areconstituted by the transistor structure 20 a or 20 b and theferroelectric capacitor structure 30, and the transistor structure 20 cor 20 d and the ferroelectric capacitor structure 50.

Description will be given about the size of the ferroelectric capacitorstructure of the stack type FeRAM according to the present embodimentformed as an above-described manner on the basis of the comparison witha stack type FeRAM of single layer structure according to a conventionalmethod.

FIGS. 8A to 8B are general plan view showing a layout in the vicinity ofthe ferroelectric capacitor structure of a FeRAM, wherein FIG. 8A showsthe FeRAM of 2-layered structure according to the first embodiment (forexample, the portion of lower layer capacitor layer 40 in FIGS. 19A to19C), and FIG. 8B shows an FeRAM of a single layer structure accordingto a conventional method, respectively. For the sake of simplicity ofillustration, in FIG. 8B, respective constructional elementscorresponding to those in FIG. 8A are given the same symbols.

Table 1 shows respective clearances and the like in the vicinity of theferroelectric capacitor structure.

TABLE 1 Present Conventional Invention Type Unit Cell Area 1 × 1.48 =1.48 μm² 1 × 1.2 = 1.2 μm² Upper Electrode 0.7 × 0.98 = 0.686 μm² 0.7 ×0.7 = 0.49 μm² Area Margin to H 0.13 μm, H 0.13 μm, Adjacent Cell W 0.12μm W 0.12 μm Plug 42-Gate 0.17 μm 0.17 μm Distance Plug 36-Gate 0.13 μm0.13 μm Distance Plug 36-Upper 0.255 μm 0.255 μm Electrode Distance

For an FeRAM of single layer structure according to a conventionalmethod, the occupying area of ferroelectric capacitor structure 30 is0.49 μm². On the contrary, for the FeRAM of 2-layered structureaccording to the present embodiment, the occupying area of ferroelectriccapacitor structure 30 becomes 0.686 μm² while maintaining the sameinterplug distance as that of a conventional FeRAM. Consequently, in thepresent embodiment, it is possible to enlarge the occupying area of theferroelectric capacitor structure 30 by around 40% compared with theconventional example. When assuming the same charge quantity per unitarea for the present embodiment and the conventional example, it ispossible to increase charge quantity per one memory cell by around 40%to make further miniaturization of an FeRAM possible.

Incidentally, in the present embodiment, the case is exemplified wherethe lower layer capacitor layer 40 and the upper layer capacitor layer60 having different heights from the surface of semiconductor substrate10 respectively are laminated into a 2-layered structure, however thepresent invention is not restricted to this constitution. For example, astructure having such construction that respective capacitor layers arelaminated by three layers or more may be acceptable.

As described above, according to the present embodiment, it becomespossible to realize miniaturization/high integration and increase inquantity of accumulated charges, and to give a stack type FeRAM having ahigh reliability.

MODIFIED EXAMPLES

Here, various modified examples of the first embodiment will bedescribed. In these modified examples, stack type FeRAMs are disclosedas is the case for the first embodiment. In this connection, for thesake of simplicity of description, constructional elements similar tothose described in the first embodiment will be given the same symbolsas those in the first embodiment.

Modified Example 1

In the modified example 1, a protective insulating film for suppressingintrusion of hydrogen into the ferroelectric film is formed.

FIGS. 9A to 11B are general cross-sectional views showing theconstitution of the stack type FeRAM according to the modified example 1of the first embodiment along with its manufacturing method according tothe order of the steps.

Firstly, as is the case for the first embodiment, the ferroelectriccapacitor structure 30 is formed through respective steps of FIGS. 1A to3A.

Subsequently, as shown in FIG. 9A, a protective insulating film 91covering the ferroelectric capacitor structure 30 is formed.

More specifically, so as to cover the ferroelectric capacitor structure30, a metal oxide film, for example, using alumina as a material isdeposited on the plasma TEOS film 38 in a thickness of around 30 nm by asputtering method to form the protective insulating film 91. By theprotective insulating film 91, intrusion of moisture/hydrogen, forexample, from a silicon oxide film or the like formed in a later stepinto the ferroelectric film 45 is suppressed, and damage to theferroelectric film 45 is prevented.

Subsequently, as shown in FIG. 9B, the first interlayer insulating film49 covering the ferroelectric capacitor structure 30 via the protectiveinsulating film 91 is formed.

More specifically, for example, by a high density plasma (HDP) CVDmethod, a silicon oxide film is deposited in a thickness of around 1300nm so as to cover the ferroelectric capacitor structure 30 via theprotective insulating film 91, followed by flattening the surface of thesilicon oxide film by CMP to form the first interlayer insulating film49. In the first interlayer insulating film 49, plural (2 in theillustrated example) ferroelectric capacitor structures 30 areencapsulated via the protective insulating film 91. On this occasion,the lower layer capacitor layer 70 is constituted by the ferroelectriccapacitor structure 30, the protective insulating film 91 and the firstinterlayer insulating film 49.

Subsequently, as shown in FIG. 9C, the plugs 57, 58 are formed.

More specifically, firstly, by lithography and dry etching, the firstinterlayer insulating film 49 is patterned at a site matching with theupside of the upper electrode 52 of the ferroelectric capacitorstructure 30 to form the via hole 53 capable of exposing a part of thesurface of the upper electrode 52.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 30, an oxygen annealing treatment iscarried out. Here, for example, an annealing treatment at a treatmenttemperature of 500° C. in oxygen atmosphere for 60 minutes is carriedout. In the present embodiment, since the protective base film 43 isdisposed between the ferroelectric capacitor structure 30 and the plug42, abnormal oxidation of the plug 42 is prevented even when the oxygenannealing treatment is carried out. Together with that, generation ofhydrogen taken in the plug 42 upon forming the plug 42 is suppressed bythe protective base film 43.

Next, by lithography and dry etching, the first interlayer insulatingfilm 49, the protective insulating film 91, the plasma TEOS film 38 andthe anti-oxidizing film 37 are patterned at a site matching with theupside of the plug 36 to form a via hole 54 capable of exposing at leasta part of the surface of the plug 36.

Next, so as to cover respective wall faces of the via holes 53, 54, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form the base films (glue film) 55, 56. Then, so asto embed the via holes 53, 54 via the glue films 55, 56, a single filmor a laminated film of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here aW film is formed by a CVD method. After that, the W film and the gluefilms 55, 56 are polished by CMP using the first interlayer insulatingfilm 49 as a stopper to form the plugs 57, 58 embedding the inside ofthe via holes 53, 54 with W via the glue films 55, 56 respectively.Respective plugs 57 are connected with the upper electrode 52 of theferroelectric capacitor structure 30, and respective plugs 58 areconnected with the plug 36.

Subsequently, as shown in FIG. 10A, respective plugs 64 to be connectedwith the anti-oxidizing film 59, the plasma TEOS film 61 and a part ofthe plugs 58, and the ferroelectric capacitor structure 50 are formedsequentially.

More specifically, firstly, the anti-oxidizing film 59 of the plugs 57,58 is formed in a thickness of around 130 nm, for example, using SiON asa material by a CVD method or the like.

Next, by a plasma CVD method, the plasma TEOS film 61 having a thicknessof around 200 nm is formed.

Next, the plasma TEOS film 59 and the anti-oxidizing film 61 areprocessed by lithography and subsequent dry etching to form the via hole62 capable of exposing the surface of a part of plugs 58 respectively.

Next, so as to cover respective wall faces of the via hole 62, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form the base film (glue film) 63. Then, so as toembed the via hole 62 via the glue film 63, a single film or a laminatedfilm of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a W film isformed by a CVD method. After that, the W film and the glue film 63 arepolished by CMP using the plasma TEOS film 61 as a stopper to form theplug 64 embedding the inside of the via hole 62 with W via the glue film63.

Next, in order to suppress both of abnormal oxidation of the plug 64caused by an after-mentioned oxygen annealing treatment of theferroelectric film 67 and influence of hydrogen taken in the plug 64upon forming the plug 64 on the ferroelectric film 67, the protectivebase film 65 being a conductive film is formed in a thickness of around100 nm, for example, by a sputtering method. As a material of theprotective base film 65, a single layer of TiAlN, a laminated structureof TiN and TiAlN or the like, here a laminated structure of TiN andTiAlN is selected.

Next, by a sputtering method, Ir as an example is deposited in athickness of around 100 nm to form the lower electrode layer 66.

Next, by an MOCVD method, the ferroelectric film 67 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 66 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 67 is in an amorphous state in the initial phase of film formation,the ferroelectric film 67 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 67 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 67 in athickness of around 100 nm to form the lower layer upper electrode layer68.

Then, by a sputtering method, for example, Ir is deposited on the lowerlayer upper electrode layer 68 in a thickness of around 100 nm to formthe upper electrode layer 69.

In this connection, as a material of the lower electrode layer 66, theferroelectric film 67, the lower layer upper electrode layer 68 and theupper layer upper electrode layer 69, including the above-describedcase, at least one selected from Ir, IrOx (typically x=2), Pt, SRO, LNO,LSCO, Ru, RuO₂, SrRuO₃ and the like is used respectively.

Next, on the upper layer upper electrode layer 69, for example, a TEOSfilm is deposited in a thickness of around 600 nm by a CVD method or thelike to form the hard mask material 71.

Next, using the hard mask material 71, the upper layer upper electrodelayer 69, the lower layer upper electrode layer 68, the ferroelectricfilm 67, the lower electrode layer 66 and the protective base film 65are etched altogether, for example, at 400° C. Then, by removing thehard mask material 71 by wet etching or the like, the ferroelectriccapacitor structure 50 is completed in the P active area via the plug 64and the protective base film 65, the structure being constituted bysandwiching the ferroelectric film 67 with the lower electrode 72composed of the lower electrode layer 66, and the upper electrode 73being a laminated structure of the lower layer upper electrode layer 68and the upper layer upper electrode layer 69.

Subsequently, as shown in FIG. 10B, a protective insulating film 92 andthe second interlayer insulating film 74 covering the ferroelectriccapacitor structure 50 are formed.

More specifically, so as to cover the ferroelectric capacitor structure50, a metal oxide film, for example, using alumina as a material isdeposited on the plasma TEOS film 61 in a thickness of around 30 nm by asputtering method to form the protective insulating film 92. By theprotective insulating film 92, intrusion of moisture/hydrogen, forexample, from a silicon oxide film or the like formed in a later stepinto the ferroelectric film 67 is suppressed, and damage to theferroelectric film 67 is prevented.

Next, for example, by a high density plasma (HDP) CVD method, a siliconoxide film is deposited in a thickness of around 1300 nm so as to coverthe ferroelectric capacitor structure 50, followed by flattening thesurface of the silicon oxide film by CMP to form the second interlayerinsulating film 74. In the second interlayer insulating film 74, plural(2 in the illustrated example) ferroelectric capacitor structures 50 areencapsulated via the protective insulating film 92. On this occasion,the upper layer capacitor layer 80 lying above the lower layer capacitorlayer 70 is constituted by the ferroelectric capacitor structure 50, theprotective insulating film 92 and the second interlayer insulating film74.

Subsequently, as shown in FIG. 11A, respective plugs 82 to be connectedwith the upper electrode 73 of the ferroelectric capacitor structure 50and respective plugs 84 to be connected with the plugs 58 are formed.

More specifically, firstly, by lithography and dry etching, the secondinterlayer insulating film 74 and the protective insulating film 92 arepatterned at a site matching with the upside of the upper electrode 73of the ferroelectric capacitor structure 50 to form the via hole 75capable of exposing a part of the surface of the upper electrode 73.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 50, an oxygen annealing treatment iscarried out. In the present embodiment, since the protective base film65 is disposed between the ferroelectric capacitor structure 50 and theplug 64, abnormal oxidation of the plug 64 is prevented even when theoxygen annealing treatment is carried out. Together with that,generation of hydrogen taken in the plug 64 upon forming the plug 64 issuppressed by the protective base film 65.

Next, by lithography and dry etching, the second interlayer insulatingfilm 74, the protective insulating film 92, the plasma TEOS film 61 andthe anti-oxidizing film 59 are patterned at a site matching with theupside of the plugs 57, 58 to form the via holes 76, 77 capable ofexposing at least a part of the surface of the plugs 57, 58.

Next, so as to cover respective wall faces of the via holes 75, 76, 77,for example, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form the base films (glue film) 78, 79, 81. Then,so as to embed the via holes 75, 76, 77 via the glue films 78, 79, 81, asingle film or a laminated film of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO orIr, here a W film is formed by a CVD method. After that, the W film andthe glue films 78, 79, 81 are polished by CMP using the secondinterlayer insulating film 74 as a stopper to form the plugs 82, 83, 84embedding the inside of the via holes 75, 76, 77 with W via the gluefilms 78, 79, 81 respectively.

Subsequently, as shown in FIG. 11B, the bit wire 88 to be connected withthe plug 84, and the plate wire 89 to be connected with the plugs 82, 83are formed respectively.

More specifically, firstly, by a sputtering method, for example, TiN isdeposited in a thickness of around 60 nm to form the barrier metal film85.

Next, by a sputtering method, for example, an Al—Cu alloy is depositedin a thickness of around 360 nm to form a wiring layer 86.

Next, by a sputtering method, for example, a laminated film of TiN andTi is deposited in a thickness of around 70 nm to form the barrier metalfilm 87.

Next, the barrier metal film 87, the wiring layer 86 and the barriermetal film 85 are patterned by lithography and dry etching. By thispattering, respective bit wires 88 to be connected with the plug 84, andrespective plate wires 89 to be connected with the plugs 82, 83 areformed.

After that, through the formation of an interlayer insulating film, anupper layer wiring, a protective insulating film and the like, the stacktype FeRAM according to the modified example 1 is completed. In theillustrated example, respective memory cells of the 1T1C structure areconstituted by the transistor structure 20 a or 20 b and theferroelectric capacitor structure 30, and the transistor structure 20 cor 20 d and the ferroelectric capacitor structure 50.

As described above, according to the present example, in addition tovarious advantages exerted by the first embodiment, it becomes possibleto suppress inclusion of hydrogen into the ferroelectric films 45, 67 asfar as possible, and realize an FeRAM having a high reliability.

Modified Example 2

In the modified example 2, a protective base film for suppressingabnormal oxidation of the plug as well as suppressing incursion ofhydrogen into the ferroelectric film is formed.

FIGS. 12A to 15C are general cross-sectional views showing theconstitution of the stack type FeRAM according to the modified example 2of the first embodiment along with its manufacturing method according tothe order of the steps.

Firstly, as is the case for the first embodiment, the plugs 36, 42 areformed through respective steps in FIGS. 1A to 2A.

Subsequently, as shown in FIG. 12A, the protective base film 43, thelower electrode layer 44, the ferroelectric film 45 and an upperelectrode layer 121 for forming an after-mentioned ferroelectriccapacitor structure 100 are formed respectively.

More specifically, firstly, in order to suppress both of abnormaloxidation of the plug 42 caused by an after-mentioned oxygen annealingtreatment of the ferroelectric film 45 and influence of hydrogen takenin the plug 42 upon forming the plug 42 on the ferroelectric film 45,the protective base film 43 being a conductive film is formed in athickness of around 100 nm, for example, by a sputtering method. As amaterial of the protective base film 43, a single layer of TiAlN, alaminated structure of TiN and TiAlN or the like, here a laminatedstructure of TiN and TiAlN is selected.

Next, by a sputtering method, Ir as an example is deposited in athickness of around 100 nm to form the lower electrode layer 44.

Next, by an MOCVD method, the ferroelectric film 45 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 44 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 45 is in an amorphous state in the initial phase of film formation,the ferroelectric film 45 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 45 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 45 in athickness of around 100 nm to form the upper electrode layer 121. In thepresent embodiment, an after-mentioned protective base film 98 is formedon an after-mentioned upper electrode 122, thus such conformation that aplug for connection is formed directly on the upper electrode 122 is notadopted. Consequently, apprehension is unnecessary for the etching ofthe upper electrode 122 at plug formation, and the upper electrode layer121 alone is sufficient as an upper electrode material that becomes theupper electrode 52.

In this connection, as a material of the lower electrode layer 44, theferroelectric film 45 and the upper electrode layer 121, including theabove-described case, at least one selected from Ir, IrOx (typicallyx=2), Pt, SRO, LNO, LSCO, Ru, RuO₂, SrRuO₃ and the like is usedrespectively.

Next, on the upper layer upper electrode layer 47, for example, a TEOSfilm is deposited in a thickness of around 600 nm by a CVD method or thelike to form the hard mask material 48.

Subsequently, as shown in FIG. 12B, after forming the ferroelectriccapacitor structure 100 of a lower layer, a first interlayer insulatingfilm 93 capable of exposing the surface of the ferroelectric capacitorstructure 100 (surface of the upper electrode 122) is formed.

More specifically, using the hard mask material 48, the upper electrodelayer 121, the ferroelectric film 45, the lower electrode layer 44 andthe protective base film 43 are etched altogether, for example, at 400°C. Then, by removing the hard mask material 48 by wet etching or thelike, the ferroelectric capacitor structure 100 is completed in the Nactive area via the plug 42 and the protective base film 43, thestructure being constituted by sandwiching the ferroelectric film 45with the lower electrode 51 composed of the lower electrode layer 44,and the upper electrode 122 composed of the upper electrode layer 121.

Next, for example, by a high density plasma (HDP) CVD method, a siliconoxide film is deposited in a thickness of around 1300 nm so as to coverthe ferroelectric capacitor structure 100, followed by flattening thesurface of the silicon oxide film by CMP using the surface of the upperelectrode 122 as a polishing stopper. On this occasion, the firstinterlayer insulating film 93 encapsulating plural (2 in the illustratedexample) ferroelectric capacitor structures 100 in such state that thesurface of the upper electrode 52 is exposed are formed. Here, the lowerlayer capacitor layer 90 is constituted by the ferroelectric capacitorstructure 100 and the first interlayer insulating film 93.

Subsequently, as shown in FIG. 12C, the via hole 94 is formed.

More specifically, by lithography and dry etching, the first interlayerinsulating film 93, the plasma TEOS film 38 and the anti-oxidizing film37 are patterned at a site matching with the upside of the plug 36 toform a via hole 94 capable of exposing a part of the surface of the plug36.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 100, an oxygen annealing treatment iscarried out. Here, for example, an annealing treatment at a treatmenttemperature of 500° C. in oxygen atmosphere for 60 minutes is carriedout. In the present embodiment, since the protective base film 43 isdisposed between the ferroelectric capacitor structure 100 and the plug42, abnormal oxidation of the plug 42 is prevented even when the oxygenannealing treatment is carried out. Together with that, generation ofhydrogen taken in the plug 42 upon forming the plug 42 is suppressed bythe protective base film 43.

Subsequently, as shown in FIG. 13A, respective plugs 96 connected withthe plug 36 are formed.

More specifically, so as to cover respective wall faces of the via hole94, for example, a TiN film is deposited in a thickness of around 75 nmby a sputtering method to form a base film (glue film) 95. Then, so asto embed the via hole 94 via the glue film 95, a single film or alaminated film of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a Wfilm is formed by a CVD method. After that, the W film and the glue film95 are polished by CMP using the first interlayer insulating film 93 asa stopper to form the plug 96 embedding the inside of the via hole 94with W via the glue film 95 respectively.

Subsequently, as shown in FIG. 13B, a conductive layer 97 to become anafter-mentioned protective base film is formed.

More specifically, by a sputtering method, the conductive layer 97having a thickness of around 100 nm is formed on the lower layercapacitor layer 90, for example, using TiAlN as a material. Here, as amaterial of the conductive layer 97, a laminated structure of TiN andTiAlN, Ir or the like may be used instead of TiAlN.

Subsequently, as shown in FIG. 13C, the conductive layer 97 is patternedto form respective protective base films 98.

More specifically, the conductive layer 97 is patterned by lithographyand dry etching to form respective protective base films 98 having asize, for example, matching with the upper surface shape of respectiveplugs 96 (the same size also on the ferroelectric capacitor structure30). By these protective base films 98, both of abnormal oxidation ofthe plug 96 caused by an after-mentioned oxygen annealing treatment ofthe ferroelectric film 67, and influence of hydrogen taken in the plug96 upon forming the plug 96 on the ferroelectric film 67 are suppressed.

Subsequently, as shown in FIG. 14A, the plasma TEOS film 99 capable ofexposing the surface of respective protective base films 98 is formed.

More specifically, so as to cove respective protective base films 98,the plasma TEOS film 99 having a thickness of around 800 nm is formed bya plasma CVD method. After that, using respective protective base films98 as a polishing stopper, the plasma TEOS film 99 is flattened by CMP.

Subsequently, as shown in FIG. 14B, after forming the lower electrodelayer 66, the ferroelectric film 67, the lower layer upper electrodelayer 68 and the upper layer upper electrode layer 69 respectively, thehard mask material 71 is formed.

More specifically, firstly, by a sputtering method, Ir as an example isdeposited in a thickness of around 100 nm to form the lower electrodelayer 66.

Next, by an MOCVD method, the ferroelectric film 67 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 66 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 67 is in an amorphous state in the initial phase of film formation,the ferroelectric film 67 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 67 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 67 in athickness of around 100 nm to form the lower layer upper electrode layer68.

Then, by a sputtering method, for example, Ir is deposited on the lowerlayer upper electrode layer 68 in a thickness of around 100 nm to formthe upper electrode layer 69.

In this connection, as a material of the lower electrode layer 66, theferroelectric film 67, the lower layer upper electrode layer 68 and theupper layer upper electrode layer 69, including the above-describedcase, at least one selected from Ir, IrOx (typically x=2), Pt, SRO, LNO,LSCO, Ru, RuO₂, SrRuO₃ and the like is used respectively.

Next, on the upper layer upper electrode layer 69, for example, a TEOSfilm is deposited in a thickness of around 600 nm by a CVD method or thelike to form the hard mask material 71.

Subsequently, as shown in FIG. 14C, the ferroelectric capacitorstructure 50 is formed.

More specifically, using the hard mask material 71, the upper layerupper electrode layer 69, the lower layer upper electrode layer 68, theferroelectric film 67 and the lower electrode layer 66 are etchedaltogether, for example, at 400° C. Then, by removing the hard maskmaterial 71 by wet etching or the like, the ferroelectric capacitorstructure 50 is completed in the P active area, the structure beingconstituted by sandwiching the ferroelectric film 67 with the lowerelectrode 72 composed of the lower electrode layer 66, and the upperelectrode 73 being a laminated structure of the lower layer upperelectrode layer 68 and the upper layer upper electrode layer 69.

Subsequently, as shown in FIG. 15A, the second interlayer insulatingfilm 74 covering the ferroelectric capacitor structure 50 is formed.

More specifically, for example, by a high density plasma (HDP) CVDmethod, a silicon oxide film is deposited in a thickness of around 1300nm so as to cover the ferroelectric capacitor structure 50, followed byflattening the surface of the silicon oxide film by CMP to form thesecond interlayer insulating film 74. In the second interlayerinsulating film 74, plural (2 in the illustrated example) ferroelectriccapacitor structures 50 are encapsulated. On this occasion, the upperlayer capacitor layer 60 lying above the lower layer capacitor layer 90is constituted by the ferroelectric capacitor structure 50 and thesecond interlayer insulating film 74.

Subsequently, as shown in FIG. 15B, respective plugs 107 to be connectedwith the upper electrode 73 of the ferroelectric capacitor structure 50,respective plugs 108 to be connected with the upper electrode 52 of theferroelectric capacitor structure 30 via the protective base film 98,and respective plugs 109 to be connected with the plug 96 via theprotective base film 98 are formed.

More specifically, firstly, by lithography and dry etching, the secondinterlayer insulating film 74 is patterned at a site matching with theupside of the upper electrode 73 of the ferroelectric capacitorstructure 50 to form the via hole 101 capable of exposing a part of thesurface of the upper electrode 73.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 50, an oxygen annealing treatment iscarried out. In the present embodiment, since the protective base film98 is disposed between the ferroelectric capacitor structure 50 and theplug 96, abnormal oxidation of the plug 96 is prevented even when theoxygen annealing treatment is carried out. Together with that,generation of hydrogen taken in the plug 96 upon forming the plug 96 issuppressed by the protective base film 98.

Next, by lithography and dry etching, the second interlayer insulatingfilm 74 is patterned at a site matching with the upside of respectiveprotective base films 98 to form via holes 102, 103 capable of exposingat least a part of the surface of the protective base film 98respectively.

Next, so as to cover respective wall faces of the via holes 101, 102,103, for example, a TiN film is deposited in a thickness of around 75 nmby a sputtering method to form base films (glue film) 104, 105, 106.Then, so as to embed the via holes 101, 102, 103 via the glue films 104,105, 106, a single film or a laminated film of W, TiAlN, TiN, Ti, Al,Cu, Ru, SRO or Ir, here a W film is formed by a CVD method. After that,the W film and the glue films 104, 105, 106 are polished by CMP usingthe second interlayer insulating film 74 as a stopper to form the plugs107, 108, 109 embedding the inside of the via holes 101, 102, 103 with Wvia the glue films 104, 105, 106 respectively.

Subsequently, as shown in FIG. 15C, the bit wire 88 to be connected withthe plug 109 and the plate wires 89 to be connected with the plugs 107,108 are formed respectively.

More specifically, firstly, by a sputtering method, for example, TiN isdeposited in a thickness of around 70 nm to form the barrier metal film85.

Next, by a sputtering method, for example, an Al—Cu alloy is depositedin a thickness of around 360 nm to form the wiring layer 86.

Next, by a sputtering method, for example, a laminated film of TiN andTi is deposited in a thickness of around 70 nm to form the barrier metalfilm 87.

Next, the barrier metal film 87, the wiring layer 86 and the barriermetal film 85 are patterned by lithography and dry etching. By thepatterning, respective bit wires 88 to be connected with the plug 109,and respective plate wires 89 to be connected with the plugs 107, 108are formed.

After that, through the formation of an interlayer insulating film, anupper layer wiring, a protective insulating film and the like, the stacktype FeRAM according to the modified example 2 is completed. In theillustrated example, respective memory cells of the 1T1C structure areconstituted by the transistor structure 20 a or 20 b and theferroelectric capacitor structure 100, and the transistor structure 20 cor 20 d and the ferroelectric capacitor structure 50.

As described above, according to the present example, in addition tovarious advantages exerted by the first embodiment, it becomes possibleto suppress inclusion of hydrogen into the ferroelectric films 45, 67 asfar as possible as well as to suppress generation of hydrogen from theplug 96 as far as possible, and to realize an FeRAM having a highreliability.

Modified Example 3

In the modified example 3, such constitution is adopted that aferroelectric capacitor structure of respective memory cells isalternately arranged adjacent to a lower layer capacitor layer and anupper layer capacitor layer. Further characteristics of the modifiedexample 2 are added.

FIGS. 16A to 20B are general cross-sectional views showing theconstitution of the stack type FeRAM according to the modified example 3of the first embodiment as well as its manufacturing method according tothe order of the steps.

Firstly, as is the case for the first embodiment, the protective film 21and the insulating film 22 of the transistor structures 20 a, 20 b, 20c, 20 d are formed through respective steps of FIGS. 1A, 1B.

Subsequently, as shown in FIG. 16A, respective plugs 36 to be connectedwith either of the source/drain area 18 a of the transistor structure 20a, either of the source/drain area 18 b of the transistor structure 20c, and the source/drain areas 18 a, 18 b of the transistor structures 20b and 20 d are formed.

Firstly, respective via holes 34 to the transistor structures 20 a, 20b, 20 c, 20 d are formed.

More specifically, the insulating film 22 and the protective film 21 areprocessed by lithography and subsequent dry etching to form the viaholes 34 capable of exposing either of the source/drain area 18 a of thetransistor structure 20 a, either of the source/drain area 18 b of thetransistor structure 20 c, and a part of the surface of the source/drainareas 18 a, 18 b of the transistor structures 20 b, 20 d.

Next, so as to cover respective wall faces of the via hole 34, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form the base film (glue film) 35. Then, so as toembed the via hole 34 via the glue film 35, a single film or a laminatedfilm of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a W film isformed by a CVD method. After that, the W film and the glue film 35 arepolished by CMP using the insulating film 21 as a stopper to form theplug 36 embedding the inside of the via hole 34 with W via the glue film35.

Subsequently, as shown in FIG. 16B, after forming the anti-oxidizingfilm 37 and the plasma TEOS film 38, respective plugs 42 to be connectedwith the other of the source/drain area 18 a of the transistor structure20 a and the other of the source/drain area 18 b of the transistorstructure 20 c are formed.

More specifically, firstly, the anti-oxidizing film 37 of the plug 36 isformed, for example, using SiON as a material in a thickness of around130 nm by a CVD method or the like

Next, by a plasma CVD method, the plasma TEOS film 38 having a thicknessof around 200 nm is formed.

Next, the plasma TEOS film 38, the anti-oxidizing film 37, theinsulating film 22, and the protective film 21 are processed bylithography and subsequent dry etching to form the via hole 39 capableof exposing a part of the other surface of the source/drain area 18 a ofthe transistor structure 20 a, and a part of the other surface of thesource/drain area 18 b of the transistor structure 20 c respectively.

Next, so as to cover respective wall faces of the via hole 39, forexample, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form the base film (glue film) 41. Then, so as toembed the via hole 39 via the glue film 41, a single film or a laminatedfilm of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a W film isformed by a CVD method. After that, the W film and the glue film 41 arepolished by CMP using the plasma TEOS film 38 as a stopper to form theplug 42 embedding the inside of the via hole 39 with W via the glue film41.

Subsequently, as shown in FIG. 16C, the protective base film 43, thelower electrode layer 44, the ferroelectric film 45 and the upperelectrode layer 121 for forming an after-mentioned ferroelectriccapacitor structure 100 are formed respectively.

More specifically, firstly, in order to suppress both of abnormaloxidation of the plug 42 caused by an after-mentioned oxygen annealingtreatment of the ferroelectric film 45 and influence of hydrogen takenin the plug 42 upon forming the plug 42 on the ferroelectric film 45,the protective base film 43 being a conductive film is formed in athickness of around 100 nm, for example, by a sputtering method. As asubstance of the protective base film 43, a single layer of TiAlN, alaminated structure of TiN and TiAlN or the like, here a laminatedstructure of TiN and TiAlN is selected.

Next, by a sputtering method, Ir as an example is deposited in athickness of around 100 nm to form the lower electrode layer 44.

Next, by an MOCVD method, the ferroelectric film 45 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 44 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 45 is in an amorphous state in the initial phase of film formation,the ferroelectric film 45 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 45 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 45 in athickness of around 100 nm to form the upper electrode layer 121. In thepresent embodiment, an after-mentioned protective base film 98 is formedon an after-mentioned upper electrode 122, thus such conformation that aplug for connection is formed directly on the upper electrode 122 is notadopted. Consequently, apprehension is unnecessary for the etching ofthe upper electrode 122 at plug formation, and the upper electrode layer121 alone is sufficient as an upper electrode material that becomes theupper electrode 52.

In this connection, as a material of the lower electrode layer 44, theferroelectric film 45 and the upper electrode layer 121, including theabove-described case, at least one selected from Ir, IrOx (typicallyx=2), Pt, SRO, LNO, LSCO, Ru, RuO₂, SrRuO₃ and the like is usedrespectively.

Next, on the upper layer upper electrode layer 47, for example, a TEOSfilm is deposited in a thickness of around 600 nm by a CVD method or thelike to form the hard mask material 48.

Subsequently, as shown in FIG. 17A, after forming the ferroelectriccapacitor structure 100 of a lower layer, the first interlayerinsulating film 93 capable of exposing the surface of the ferroelectriccapacitor structure 100 (surface of the upper electrode 122) is formed.

More specifically, using the hard mask material 48, the upper electrodelayer 121, the ferroelectric film 45, the lower electrode layer 44 andthe protective base film 43 are etched altogether, for example, at 400°C. Then, by removing the hard mask material 48 by wet etching or thelike, the ferroelectric capacitor structure 100 is completed in the Nactive area and the P active area, respectively, via the plug 42 and theprotective base film 43, the structure being constituted by sandwichingthe ferroelectric film 45 with the lower electrode 51 composed of thelower electrode layer 44, and the upper electrode 122 composed of theupper electrode layer 121.

Next, for example, by a high density plasma (HDP) CVD method, a siliconoxide film is deposited in a thickness of around 1300 nm so as to coverthe ferroelectric capacitor structure 100, followed by flattening thesurface of the silicon oxide film by CMP using the surface of the upperelectrode 122 as a polishing stopper. On this occasion, the firstinterlayer insulating film 93 encapsulating plural (2 in the illustratedexample) ferroelectric capacitor structures 100 in such state that thesurface of the upper electrode 52 is exposed are formed. Here, a lowerlayer capacitor layer 110 is constituted by the ferroelectric capacitorstructure 100 and the first interlayer insulating film 93.

Subsequently, as shown in FIG. 17B, the via hole 94 is formed.

More specifically, by lithography and dry etching, the first interlayerinsulating film 93, the plasma TEOS film 38 and the anti-oxidizing film37 are patterned at a site matching with the upside of the plug 36 toform the via hole 94 capable of exposing a part of the surface of theplug 36.

Subsequently, as shown in FIG. 17C, respective plugs 96 to be connectedwith the plug 36 are formed.

More specifically, so as to cover respective wall faces of the via hole94, for example, a TiN film is deposited in a thickness of around 75 nmby a sputtering method to form the base film (glue film) 95. Then, so asto embed the via hole 94 via the glue film 95, a single film or alaminated film of W, TiAlN, TiN, Ti, Al, Cu, Ru, SRO or Ir, here a Wfilm is formed by a CVD method. After that, the W film and the glue film95 are polished by CMP using the first interlayer insulating film 93 asa stopper to form the plug 96 embedding the inside of the via hole 94with W via the glue film 95 respectively.

Subsequently, as shown in FIG. 18A, the conductive layer 97 to become anafter-mentioned protective base film is formed.

More specifically, by a sputtering method, the conductive layer 97having a thickness of around 100 nm is formed on a lower layer capacitorlayer 110, for example, using TiAlN as a material. Here, as a materialof the conductive layer 97, a laminated structure of TiN and TiAlN, Iror the like may be used instead of TiAlN.

Subsequently, as shown in FIG. 18B, the conductive layer 97 is patternedto form respective protective base films 98.

More specifically, the conductive layer 97 is patterned by lithographyand dry etching to form respective protective base films 98 having asize, for example, matching with the upper surface shape of respectiveplugs 96 (the same size also on the ferroelectric capacitor structure30). By these protective base films 98, both of abnormal oxidation ofthe plug 96 caused by an after-mentioned oxygen annealing treatment ofthe ferroelectric film 67, and influence of hydrogen taken in the plug96 upon forming the plug 96 on the ferroelectric film 67 are suppressed.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 30, an oxygen annealing treatment iscarried out. In the present embodiment, since the protective base film43 is disposed between the ferroelectric capacitor structure 30 and theplug 42, abnormal oxidation of the plug 42 is prevented even when theoxygen annealing treatment is carried out. Together with that,generation of hydrogen taken in the plug 42 upon forming the plug 42 issuppressed by the protective base film 43.

Subsequently, as shown in FIG. 18C, the plasma TEOS film 99 capable ofexposing the surface of respective protective base films 98 is formed.

More specifically, so as to cover respective protective base films 98,the plasma TEOS film 99 having a thickness of around 1300 nm is formedby a plasma CVD method. After that, using respective protective basefilms 98 as a stopper, the plasma TEOS film 99 is flattened by CMP.

Subsequently, as shown in FIG. 19A, after forming the lower electrodelayer 66, the ferroelectric film 67, the lower layer upper electrodelayer 68 and the upper layer upper electrode layer 69 respectively, thehard mask material 71 is formed.

More specifically, firstly, by a sputtering method, Ir as an example isdeposited in a thickness of around 100 nm to form the lower electrodelayer 66.

Next, by an MOCVD method, the ferroelectric film 67 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 66 in a thickness of around 100 nm at around 450°C.-650° C., here at 550° C. On this occasion, when the ferroelectricfilm 67 is in an amorphous state in the initial phase of film formation,the ferroelectric film 67 is subjected to an RTA treatment tocrystallize. When the ferroelectric substance 67 has alreadycrystallized, an RTA treatment is not necessarily required.

Next, by a reactive sputtering method, for example, IrO₂ being aconductive oxide is deposited on the ferroelectric film 67 in athickness of around 100 nm to form the lower layer upper electrode layer68.

Then, by a sputtering method, for example, Ir is deposited on the lowerlayer upper electrode layer 68 in a thickness of around 100 nm to formthe upper electrode layer 69.

In this connection, as a material of the lower electrode layer 66, theferroelectric film 67, the lower layer upper electrode layer 68 and theupper layer upper electrode layer 69, including the above-describedcase, at least one selected from Ir, IrOx (typically x=2), Pt, SRO, LNO,LSCO, Ru, RuO₂, SrRuO₃ and the like is used respectively.

Next, on the upper layer upper electrode layer 69, for example, a TEOSfilm is deposited in a thickness of around 600 nm by a CVD method or thelike to form the hard mask material 71.

Subsequently, as shown in FIG. 19B, the ferroelectric capacitorstructure 50 is formed.

More specifically, using the hard mask material 71, the upper layerupper electrode layer 69, the lower layer upper electrode layer 68, theferroelectric film 67 and the lower electrode layer 66 are etchedaltogether, for example, at 400° C. Then, by removing the hard maskmaterial 71 by wet etching or the like, the ferroelectric capacitorstructure 50 is completed in the N active area and the P active arearespectively, the structure being constituted by sandwiching theferroelectric film 67 with the lower electrode 72 composed of the lowerelectrode layer 66, and the upper electrode 73 being a laminatedstructure of the lower layer upper electrode layer 68 and the upperlayer upper electrode layer 69.

Subsequently, as shown in FIG. 19C, the second interlayer insulatingfilm 74 covering the ferroelectric capacitor structure 50 is formed.

More specifically, for example, by a high density plasma (HDP) CVDmethod, a silicon oxide film is deposited in a thickness of around 1300nm so as to cover the ferroelectric capacitor structure 50, followed byflattening the surface of the silicon oxide film by CMP to form thesecond interlayer insulating film 74. In the second interlayerinsulating film 74, plural (2 in the illustrated example) ferroelectriccapacitor structures 50 are encapsulated. On this occasion, the upperlayer capacitor layer 120 lying above the lower layer capacitor layer 90is constituted by respective ferroelectric capacitor structures 50 inthe N, P active areas and the second interlayer insulating film 74.

Subsequently, as shown in FIG. 20A, respective plugs 107 to be connectedwith the upper electrode 73 of the ferroelectric capacitor structure 50,respective plugs 108 to be connected with the upper electrode 52 of theferroelectric capacitor structure 100 via the protective base film 98,and respective plugs 109 to be connected with the plug 96 via theprotective base film 98 are formed.

More specifically, firstly, by lithography and dry etching, the secondinterlayer insulating film 74 is patterned at a site matching with theupside of the upper electrode 73 of the ferroelectric capacitorstructure 50 to form the via hole 101 capable of exposing a part of thesurface of the upper electrode 73.

After that, in order to recover damage given at etching of theferroelectric capacitor structure 50, an oxygen annealing treatment iscarried out. In the present embodiment, since the protective base film98 is disposed between the ferroelectric capacitor structure 50 and theplug 96, abnormal oxidation of the plug 96 is prevented even when theoxygen annealing treatment is carried out. Together with that,generation of hydrogen taken in the plug 96 upon forming the plug 96 issuppressed by the protective base film 98.

Next, by lithography and dry etching, the second interlayer insulatingfilm 74 is patterned at a site matching with the upside of respectiveprotective base films 98 to form the via holes 102, 103 capable ofexposing at least a part of the surface of the protective base film 98respectively.

Next, so as to cover respective wall faces of the via holes 101, 102,103, for example, a TiN film is deposited in a thickness of around 75 nmby a sputtering method to form the base films (glue film) 104, 105, 106.Then, so as to embed the via holes 101, 102, 103 via the glue films 104,105, 106, a single film or a laminated film of W, TiAlN, TiN, Ti, Al,Cu, Ru, SRO or Ir, here a W film is formed by a CVD method. After that,the W film and the glue films 104, 105, 106 are polished by CMP usingthe second interlayer insulating film 74 as a stopper to form the plugs107, 108, 109 embedding the inside of the via holes 101, 102, 103 with Wvia the glue films 104, 105, 106 respectively.

Subsequently, as shown in FIG. 20B, the bit wire 88 to be connected withthe plug 109 and the plate wire 89 to be connected with the plugs 107,108 are formed respectively.

More specifically, firstly, by a sputtering method, for example, TiN isdeposited in a thickness of around 60 nm to form the barrier metal film85.

Next, by a sputtering method, for example, an Al—Cu alloy is depositedin a thickness of around 360 nm to form the wiring layer 86.

Next, by a sputtering method, for example, a laminated film of TiN andTi is deposited in a thickness of around 70 nm to form the barrier metalfilm 87.

Next, the barrier metal film 87, the wiring layer 86 and the barriermetal film 85 are patterned by lithography and dry etching. By thepatterning, respective bit wires 88 to be connected with the plug 109,and respective plate wires 89 to be connected with the plugs 107, 108are formed.

After that, through the formation of an interlayer insulating film, theupper layer wiring, the protective insulating film and the like, thestack type FeRAM according to the modified example 2 is completed. Inthe illustrated example, respective memory cells of the 1T1C structureare constituted by the transistor structure 20 a or 20 c and theferroelectric capacitor structure 100, and the transistor structure 20 bor 20 d and the ferroelectric capacitor structure 50. That is, suchconstitution is adopted that ferroelectric capacitor structures 100, 50are alternately arranged adjacent to the lower layer capacitor layer 110and the upper layer capacitor layer 120.

As described above, according to the present example, in addition tovarious advantages exerted by the first embodiment, it becomes possibleto suppress inclusion of hydrogen into the ferroelectric films 45, 67 asfar as possible as well as to suppress generation of hydrogen from theplug 96 as far as possible, and to realize an FeRAM having a highreliability.

Second Embodiment

In a second embodiment, the constitution of a planar type FeRAM and itsmanufacturing method will be described.

FIGS. 21A to 25C are general cross-sectional views showing theconstitution of the planar type FeRAM according to the second embodimentalong with its manufacturing method according to the order of the steps.

Firstly, as shown in FIG. 21A, transistor structures 220 a, 220 b tofunction as a selection transistor is formed on a silicon semiconductorsubstrate 210.

More specifically, an element isolating structure 211 is formed, forexample, by an STI (Shallow Trench Isolation) method on the superficiallayer of the silicon semiconductor substrate 210 to determine an elementactive area.

Next, the element active area is ion-implanted with an impurity, here B,for example, under conditions of a dose amount of 3.0×10¹³/cm² and anacceleration energy of 300 keV to form a well 212.

Next, by forming a thin gate insulating film 213 having a thickness ofaround 3.0 nm in the element active area by a thermal oxidation or thelike, depositing a polycrystalline silicon film having a thickness ofaround 180 nm and a silicon nitride film as an example having athickness of around 29 nm on the gate insulating film 213 by a CVDmethod, and processing the silicon nitride film, the polycrystallinesilicon film and the gate insulating film 213 into an electrode shape bylithography and subsequent dry etching, a gate electrode 214 ispattern-formed on the gate insulating film 213. Simultaneously, a capfilm 215 composed of the silicon nitride film is pattern-formed on thegate electrode 214.

Next, the element active area is ion-implanted with an impurity, hereAs, for example, under conditions of a dose amount of 5.0×10¹⁴/cm² andan acceleration energy of 10 keV using the cap film 215 as a mask toform a so-called LDD area 216.

Next, for example, a silicon oxide film is deposited on the wholesurface by a CVD method, and the silicon oxide film is subjected toso-called etch back to form a sidewall insulating film 217 while leavingthe silicon oxide film only on the side face of the gate electrode 214and the cap film 215.

Next, the element active area is ion-implanted with an impurity, here Punder such conditions as giving a higher impurity concentration thanthat in the LDD area 216, for example, a dose amount of 5.0×10¹⁴/cm² andan acceleration energy of 13 keV using the cap film 215 and the sidewallinsulating film 217 as a mask to form a source/drain area 218 to beoverlapped with the LDD area 216, thereby completing transistorstructures 220 a, 220 b.

Subsequently, as shown in FIG. 21B, a protective film 221 and aninsulating film 222 of the transistor structures 220 a, 220 b areformed.

More specifically, so as to cover the transistor structures 220 a, 220b, the protective film 221 and the insulating film 222 are depositedsequentially. Here, as the protective film 221, a silicon oxide film isused as a material to be deposited in a thickness of around 20 nm by aCVD method. As the insulating film 222, a laminated structure prepared,for example, by sequentially film-forming a plasma SiO film (thicknessof around 20 nm), a plasma SiN film (thickness of around 80 nm) and aplasma TEOS film (thickness of around 1000 nm) is formed and, after thelamination, it is polished till the thickness becomes around 700 nm byCMP.

Subsequently, as shown in FIG. 21C, an orientation improving film of alower electrode of an after-mentioned ferroelectric capacitor structure230 is formed.

More specifically, for example, a silicon oxide film is deposited on theinsulating film 222 to form the orientation improving film 223.

Subsequently, as shown in FIG. 22A, a lower electrode layer 224, aferroelectric film 225 and an upper electrode layer 226 are formedsequentially.

More specifically, firstly, for example, a Ti film having a thickness ofaround 20 nm and a Pt film having a thickness of around 150 nm aredeposited sequentially by a sputtering method to form the lowerelectrode layer 224 to a laminated structure of the Ti film and the Ptfilm.

Next, by an MOCVD method, the ferroelectric film 225 composed of, forexample, PZT being a ferroelectric substance is deposited on the lowerelectrode layer 224 in a thickness of around 200 nm at around 450°C.-550° C., here at 500° C. Then, the ferroelectric film 225 issubjected to an RTA treatment to crystallize the ferroelectric film 225.

Next, by a reactive sputtering method, an upper electrode layer 226 isdeposited, for example, using IrO₂ being a conductive oxide as amaterial on the ferroelectric film 225 in a thickness of around 200 nm.In this connection, as a material of the upper electrode layer 226, Ir,Ru, RuO₂, SrRuO₃ or other conductive oxide, or a laminated structurethereof may be used instead of IrO₂.

Subsequently, as shown in FIG. 22B, the upper electrode 231 ispattern-formed.

More specifically, the upper electrode layer 226 is processed intoplural electrode shapes by lithography and subsequent dry etching topattern-form the upper electrode 231.

Subsequently, as shown in FIG. 22C, the ferroelectric film 225 and thelower electrode layer 224 are processed to form the ferroelectriccapacitor structure 230 of a lower layer.

More specifically, firstly, the ferroelectric film 225 is processed soas to have a size slightly larger than the upper electrode 231 whilematching it with the upper electrode 231 by lithography and subsequentdry etching.

Next, the lower electrode layer 224 is processed so as to have a sizeslightly larger than the ferroelectric film 225 while matching it withthe processed ferroelectric film 225 by lithography and subsequent dryetching to pattern-form a lower electrode 232. Hereby the ferroelectriccapacitor structure 230, in which the ferroelectric film 225 and theupper electrode 231 are laminated sequentially on the lower electrode232, and the lower electrode 232 and the upper electrode 231 arecapacitively coupled via the ferroelectric film 225, is completed.

After that, in order to recover damage given at etching theferroelectric film 225, an oxygen annealing treatment is carried out.

Subsequently, as shown in FIG. 23A, after forming a protectiveinsulating film 233 covering the ferroelectric capacitor structure 230,the first interlayer insulating film 227 is formed.

More specifically, so as to cover the ferroelectric capacitor structure230, a metal oxide film, for example, using alumina as a material isdeposited on the orientation improving film 223 in a thickness of around30 nm by a sputtering method to form the protective insulating film 233.By the protective insulating film 233, intrusion of moisture/hydrogen,for example, from a silicon oxide film or the like formed in a laterstep into the ferroelectric film 225 is suppressed, and damage to theferroelectric film 225 is prevented.

Next, for example, by a high density plasma (HDP) CVD method, a siliconoxide film is deposited in a thickness of around 1300 nm so as to coverthe ferroelectric capacitor structure 230 via the protective insulatingfilm 233, followed by flattening the surface of the silicon oxide filmby CMP to form the first interlayer insulating film 227. In the firstinterlayer insulating film 227, plural (1 in the illustrated example)ferroelectric capacitor structures 230 are encapsulated via theprotective insulating film 233. On this occasion, a lower layercapacitor layer 240 is constituted by the ferroelectric capacitorstructure 230, the protective insulating film 233 and the firstinterlayer insulating film 227.

Subsequently, as shown in FIG. 23B, plugs 234, 235 to be connected withthe upper electrode 231 and the lower electrode 232 of the ferroelectriccapacitor structure 230, and a plug 236 to be connected with thesource/drain area 218 of the transistor structures 220 a, 220 b areformed.

Firstly, via holes 234 a, 235 a to the ferroelectric capacitor structure230 are formed.

More specifically, as lithography and subsequent dry etching, a processto be given to the first interlayer insulating film 227 and theprotective insulating film 233 till a part of the surface of the upperelectrode 231 is exposed, and a process to be given to the firstinterlayer insulating film 227 and the protective insulating film 233till a part of the surface of the lower electrode 232 is exposed arecarried out simultaneously to simultaneously form the via holes 234 a,235 a, for example, having a diameter of about 0.5 μm at respectivesites. Upon forming these via holes 234 a, 235 a, the upper electrode231 and the lower electrode 232 function respectively as an etchingstopper.

Next, an annealing treatment for recovering damage given to theferroelectric capacitor structure 230 in various steps after theformation of the ferroelectric capacitor structure 230 is carried out.Here, for example, an annealing treatment at a treatment temperature of500° C. in oxygen atmosphere for 60 minutes is carried out.

Next, a via hole 236 a to the source/drain area 218 of the transistorstructures 220 a, 220 b is formed.

More specifically, using the source/drain area 218 as an etchingstopper, the first interlayer insulating film 127, the protectiveinsulating film 233, the orientation improving film 223, the insulatingfilm 222 and the protective film 221 are processed by lithography andsubsequent dry etching till a part of the surface of the source/drainarea 218 is exposed to form the via hole 236 a, for example, having adiameter of about 0.3 μm.

Next, the plugs 234, 235, 236 are formed.

Firstly, after carrying out an RF pretreatment corresponding to severaltens nm in terms of etching of a usual oxide film, here around 10 nm, soas to cover respective wall faces of the via holes 234 a, 235 a, 236 a,for example, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form a base film (glue film) 241. Then, forexample, a W film is formed so as to embed the via holes 234 a, 235 a,236 a via the glue film 241 by a CVD method. After that, the W film andthe glue film 241 is polished by CMP using the first interlayerinsulating film 227 as a stopper to form the plugs 234, 235, 236embedding the inside of the via holes 234 a, 235 a, 236 a with W via theglue film 241.

Subsequently, as shown in FIG. 23C, an orientation improving film 242 ofa lower electrode of an after-mentioned ferroelectric capacitorstructure 250.

More specifically, for example, a silicon oxide film is deposited on thefirst interlayer insulating film 227 to form the orientation improvingfilm 242.

Subsequently, as shown in FIG. 24A, a lower electrode layer 243, aferroelectric film 244 and an upper electrode layer 245 are formedsequentially.

More specifically, firstly, for example, a TiN film having a thicknessof around 20 nm and a Pt film having a thickness of around 150 nm areformed sequentially by a sputtering method to form the lower electrodelayer 243 to the laminated structure of the Ti film and the Pt film.

Next, by an MOCVD method, a ferroelectric film 244 composed of, forexample, PZT being a ferroelectric substance is formed on the lowerelectrode layer 243 in a thickness of around 200 nm at around 450°C.-550° C., here at 500° C. Then, the ferroelectric film 244 issubjected to an RTA treatment to crystallize the ferroelectric film 244.

Next, by a reactive sputtering method, an upper electrode layer 245 isdeposited, for example, using IrO₂ being a conductive oxide as amaterial on the ferroelectric film 244 in a thickness of around 200 nm.In this connection, as a material of the upper electrode layer 245, Ir,Ru, RuO₂, SrRuO₃ or other conductive oxides, or a laminated structurethereof may be used instead of IrO₂.

Subsequently, as shown in FIG. 24B, an upper electrode 251 ispattern-formed.

More specifically, the upper electrode layer 245 is processed intoplural electrode shapes by lithography and subsequent dry etching topattern-form the upper electrode 251.

Subsequently, as shown in FIG. 24C, the ferroelectric film 244 and thelower electrode layer 243 are processed to form the ferroelectriccapacitor structure 250 of an upper layer.

More specifically, firstly ferroelectric film 244 is processed so as tohave a size slightly larger than the upper electrode 251 while matchingit with the upper electrode 251 by lithography and subsequent dryetching.

Next, the lower electrode layer 243 is processed so as to have a sizeslightly larger than the ferroelectric film 244 while matching it withthe processed ferroelectric film 244 by lithography and subsequent dryetching to pattern-form a lower electrode 252. Hereby the ferroelectriccapacitor structure 250, in which the ferroelectric film 244 and theupper electrode 251 are laminated sequentially on the lower electrode252, and the lower electrode 252 and the upper electrode 251 arecapacitively coupled via the ferroelectric film 244, is completed.

After that, in order to recover damage given at etching theferroelectric film 244, an oxygen annealing treatment is carried out.

Subsequently, as shown in FIG. 25A, after forming a protectiveinsulating film 253 covering the ferroelectric capacitor structure 250,a second interlayer insulating film 246 is formed.

More specifically, so as to cover the ferroelectric capacitor structure250, a metal oxide film, for example, using alumina as a material isdeposited on the orientation improving film 242 in a thickness of around30 nm by a sputtering method to form a protective insulating film 253.By the protective insulating film 253, intrusion of moisture/hydrogen,for example, from a silicon oxide film or the like formed in a laterstep into the ferroelectric film 244 is suppressed, and damage to theferroelectric film 244 is prevented.

Next, for example, by a high density plasma (HDP) CVD method, a siliconoxide film is deposited in a thickness of around 1300 nm so as to coverthe ferroelectric capacitor structure 250 via the protective insulatingfilm 253, followed by flattening the surface of the silicon oxide filmby CMP to form the second interlayer insulating film 246. In the secondinterlayer insulating film 246, plural (1 in the illustrated example)ferroelectric capacitor structures 250 are encapsulated via theprotective insulating film 253. On this occasion, an upper layercapacitor layer 260 lying above the lower layer capacitor layer 240 isconstituted by the ferroelectric capacitor structure 250, the protectiveinsulating film 253 and the first interlayer insulating film 246.

Subsequently, as shown in FIG. 25B, plugs 254, 255 to be connected withthe upper electrode 251 and the lower electrode 252 of the ferroelectriccapacitor structure 250, and a plug 256 to be connected with the plugs234, 235, 236 are formed respectively.

Firstly, via holes 254 a, 255 a to the ferroelectric capacitor structure250 are formed.

More specifically, as lithography and subsequent dry etching, a processto be given to the second interlayer insulating film 246 and theprotective insulating film 253 till a part of the surface of the upperelectrode 251 is exposed, and a process to be given to the secondinterlayer insulating film 246 and the protective insulating film 253till a part of the surface of the lower electrode 252 is exposed arecarried out simultaneously to simultaneously form the via holes 254 a,255 a, for example, having a diameter of about 0.5 μm at respectivesites. Upon forming these via holes 254 a, 255 a, the upper electrode251 and the lower electrode 252 function respectively as an etchingstopper.

Next, an annealing treatment for recovering damage given to theferroelectric capacitor structure 250 in various steps after theformation of the ferroelectric capacitor structure 250 is carried out.Here, for example, an annealing treatment at a treatment temperature of500° C. in oxygen atmosphere for 60 minutes is carried out.

Next, a via hole 256 a to the plugs 234, 235, 236 is formed.

More specifically, using the plugs 234, 235, 236 as an etching stopper,the second interlayer insulating film 246 and the protective insulatingfilm 253 are processed by lithography and subsequent dry etching till apart of the surface of the plugs 234, 235, 236 is exposed to form thevia hole 256 a, for example, having a diameter of about 0.3 μm.

Next, the plugs 254, 255, 256 are formed.

Firstly, after carrying out an RF pretreatment corresponding to severaltens nm in terms of etching of a usual oxide film, here around 10 nm, soas to cover respective wall faces of the via holes 254 a, 255 a, 256 a,for example, a TiN film is deposited in a thickness of around 75 nm by asputtering method to form a base film (glue film) 261. Then, forexample, a W film is formed so as to embed the via holes 254 a, 255 a,256 a via the glue film 261 by a CVD method. After that, the W film andthe glue film 261 is polished by CMP using the second interlayerinsulating film 246 as a stopper to form the plugs 254, 255, 256embedding the inside of the via holes 254 a, 255 a, 256 a with W via theglue film 261.

Subsequently, as shown in FIG. 25C, wirings 265 to be connected with theplugs 254, 255, 256 are formed respectively.

More specifically, firstly, by a sputtering method, for example, TiN isdeposited in a thickness of around 60 nm to form a barrier metal film262.

Next, by a sputtering method, for example, an Al—Cu alloy is depositedin a thickness of around 360 nm to form a wiring layer 263.

Next, by a sputtering method, for example, a laminated film of TiN andTi is deposited in a thickness of around 70 nm to form a barrier metalfilm 264.

Next, the barrier metal film 262, the wiring layer 263 and the barriermetal film 264 are patterned by lithography and dry etching. By thepatterning, respective wirings 265 to be connected to the plugs 254,255, 256 are formed respectively.

After that, through the formation of an interlayer insulating film, anupper layer wiring, a protective insulating film and the like, theplanar type FeRAM according to the second embodiment is completed. Inthe illustrated example, respective memory cells of the 1T1C structureare constituted respectively by the transistor structure 220 a and theferroelectric capacitor structure 250, and the transistor structure 220b and the ferroelectric capacitor structure 230.

As described above, according to the present embodiment, it becomespossible to realize miniaturization/high integration and increase in theamount of accumulated charges, and to give a planar type FeRAM having ahigh reliability.

According to the present invention, it becomes possible to realizeminiaturization/high integration and increase in an amount ofaccumulated charges, and to give a memory structure having a highreliability.

1. A semiconductor device comprising: a plurality of memory cells thatrespectively includes a capacitor structure formed above a semiconductorsubstrate and constituted by sandwiching a dielectric film with a lowerelectrode and an upper electrode, and a transistor for selecting thecapacitor structure, wherein the capacitor structure of the respectivememory cells is respectively formed in either one layer of at least twolayers of interlayer insulating films having different heights from asurface of the semiconductor substrate; wherein, between two layers ofthe interlayer insulating films having been laminated adjacently, afirst protective film is formed between the lower electrode and a firstplug, a second protective film is formed between the upper electrode andthe first plug, and a third protective film is formed between a secondplug and a third plug located lower in position than the second plug ina height, wherein the first protective film, the second protective film,and the third protective film are formed at the same position in heightfrom the surface of the semiconductor substrate.
 2. The semiconductordevice according to claim 1 comprising: a constitution wherein, as tothe respective capacitor structures, the capacitor structure neighboringsaid capacitor structure is formed in the same interlayer insulatingfilm.
 3. The semiconductor device according to claim 1 comprising: aconstitution wherein, as to the respective capacitor structures, saidcapacitor structure and said second capacitor structure neighboring saidcapacitor structure exist in the different interlayer insulating films.4. The semiconductor device according to claim 1, wherein the dielectricfilm is composed of a ferroelectric material.
 5. The semiconductordevice according to claim 4, wherein a protective insulating filmcovering the respective capacitor structures is formed in the respectiveinterlayer insulating films.
 6. The semiconductor device according toclaim 1, wherein the memory cell is a stack type one comprisingrespective plugs to a downside of the lower electrode and the upside ofthe upper electrode of the respective capacitor structures.
 7. Thesemiconductor device according to claim 1, wherein, between the lowerelectrode and the first plug of the respective capacitor structure, aprotective film having the same shape as said lower electrode is formed.8. A manufacturing method of a semiconductor device comprising aplurality of memory cells, comprising the steps of: forming a transistorabove a semiconductor substrate; forming one capacitor structureconstituted by sandwiching a dielectric film with a lower electrode andan upper electrode above the transistor so as to correspond to one ofthe transistor; forming the capacitor structure of the respective memorycells in either one layer of at least two layers of interlayerinsulating films having different heights from a surface of thesemiconductor substrate; and wherein between two layers of theinterlayer insulating films having been laminated adjacently, further,forming a first protective film between the lower electrode and a firstplug; forming a second protective film between the upper electrode andthe first plug; and forming a third protective film is formed between asecond plug and a third plug located lower in position than the secondplug in a height, wherein the first protective film, the secondprotective film, and the third protective film are formed at the sameposition in height from the surface of the semiconductor substrate. 9.The manufacturing method of a semiconductor device according to claim 8,wherein the respective capacitor structures are formed in a constitutionthat a second capacitor structure neighboring said capacitor structureis formed in the same interlayer insulating film.
 10. The manufacturingmethod of a semiconductor device according to claim 8, wherein therespective capacitor structures are formed in a constitution that saidcapacitor structure and said second capacitor structure neighboring saidcapacitor structure exist in the different interlayer insulating films.11. The manufacturing method of a semiconductor device according toclaim 8, wherein the dielectric film is formed from a ferroelectricmaterial.
 12. The manufacturing method of a semiconductor deviceaccording to claim 11 further comprising the step of: forming aprotective insulating film covering the respective capacitor structuresin the respective interlayer insulating films.
 13. The manufacturingmethod of a semiconductor device according to claim 12, wherein thedielectric film is formed by an MOCVD method.
 14. The manufacturingmethod of a semiconductor device according to claim 8, wherein thememory cell is a stack type one comprising respective plugs to adownside of the lower electrode and an upside of the upper electrode ofthe respective capacitor structures.
 15. The manufacturing method of asemiconductor device according to claim 8, further comprising the stepsof: forming a protective film, between the lower electrode and the plugof the respective capacitor structures, having the same shape as saidlower electrode.